In most cases, no. Your doctor can't usually tell, simply by looking at a polyp during a colonoscopy, if it's cancerous. But if a polyp is found during your colonoscopy, your doctor will remove it and send it to a lab for a biopsy to check for cancerous or precancerous cells.
It can be a flat bump (sessile). Or it can be shaped like a mushroom, with a bulbous head projecting from a stalk (pedunculated). Polyps range in size, from about 5 millimeters (the size of a match head) to 3 centimeters (similar to the top of your thumb) or larger.
Colon Cancer Diagnosis: Getting a Colonoscopy
Screening is crucial for cancer detection because most colorectal cancers don't cause symptoms in the early stages. Many times, doctors first spot colon cancer during a routine screening colonoscopy.
It may take up to 10 years for some polyps to become cancerous. Screening tests, including a colonoscopy, can help detect colon polyps.
If a doctor discovers polyps, they will often remove them via a colonoscopy or laparoscopy. The doctor will then send any removed polyps to a pathologist for a biopsy to see if cancer is present. If the biopsy reveals that cancer is present, then cancer specialists will outline a treatment plan for the person.
If your doctor finds precancerous polyps, there is no need for any additional treatment as long as they remove the entire polyp. Removing the tissue stops the development of cancer.
They look like bumps growing from the inside lining of the bowel protruding out. They sometimes grow on a “stalk” and look like mushrooms. Some polyps can be flat. People can have several polyps scattered in different parts of the colon.
You may be able to see a growth. Certain things about the image might even suggest that it's likely to be cancerous. But there are many benign (noncancerous) tumors that look very much like cancerous growths. That's why, if your doctor suspects cancer from imaging, they will almost always follow up with a biopsy.
How long does it take for a polyp to turn into cancer? The growth and mutation of colon polyps into cancer is a slow process, taking an estimated 10 years on average.
Signs and symptoms of colon cancer include: A persistent change in your bowel habits, including diarrhea or constipation or a change in the consistency of your stool. Rectal bleeding or blood in your stool. Persistent abdominal discomfort, such as cramps, gas or pain.
Results: Among those who underwent colonoscopic screening, 78.9 percent had no detected lesions, 10.0 percent had hyperplastic polyps, 8.7 percent had tubular adenomas, and 3.5 percent had advanced neoplasms, none of which were cancerous (95 percent confidence interval for cancer, 0 to 0.4 percent).
When a polyp is adenomatous, the color is more likely to be deep red or purple whereas the color of a non-adenomatous lesion tends to be yellow or white.
They can occur anywhere in the large intestine or rectum, but are more commonly found in the left colon, sigmoid colon, or rectum.
Depending on their size and location in the colon, serrated polyps may become cancerous. Small, serrated polyps in the lower colon, also known as hyperplastic polyps, are rarely malignant. Larger serrated polyps, which are typically flat (sessile), difficult to detect and located in the upper colon, are precancerous.
Can you diagnose without a biopsy? The short answer is no. While imaging and blood draws can show suspicious areas or levels, removing tissue and studying it is the only way to diagnose cancer 100%.
Before you go home, your doctor tells you if they removed any growths (polyps) or tissue samples (biopsies) from your bowel. The biopsy results can take up to 2 weeks.
In most situations, a biopsy is the only way to definitively diagnose cancer. In the laboratory, doctors look at cell samples under the microscope. Normal cells look uniform, with similar sizes and orderly organization. Cancer cells look less orderly, with varying sizes and without apparent organization.
Colon polyps don't usually cause symptoms. It's important to have regular screening tests because colon polyps found in the early stages can usually be removed safely and completely.
"Precancerous polyps are extremely common," he says. "We expect to find them in more than a quarter of the colonoscopies that we do at a minimum. So, you know, maybe a third or even a half of all patients getting [a] colonoscopy will have precancerous polyps."
It is considered an abnormal growth, but in many cases, they are found to be benign (commonly in the early stages). However, over time polyps can become large and malignant if they aren't treated. Many polyps are found to be pre-cancerous, which means they have the potential to turn cancerous if they aren't removed.
Colorectal cancer can occur without polyps, but it is thought to be an uncommon event. Individuals with long-standing inflammatory bowel diseases, such as chronic ulcerative colitis and Crohn's colitis, are at increased risk for developing colorectal cancer that occurs in the absence of obvious polyps.
The procedure takes between 20 minutes to one hour.
He says you might be surprised how often colonoscopies uncover polyps lurking in your colon. "Precancerous polyps are extremely common," he says. "We expect to find them in more than a quarter of the colonoscopies that we do at a minimum.